Merge remote-tracking branch 'origin/develop' into develop

* origin/develop:
  The documentation for 'Developing Salt' is missing a critical step for 0.17+ users who wish to utilize the test runner. This commit describes the direct installation of salt-testing.
  -- Please review for accuracy prior to merge --
Fix issue 5951 - correct __opts__['file_roots'] in ext_pillars
Merge pull request #7767 from dlanderson/fix_issue_5951

Fix issue 5951 - correct __opts__['file_roots'] in ext_pillars
Merge branch 'develop' of https://github.com/saltstack/salt into develop

* 'develop' of https://github.com/saltstack/salt: (193 commits)
  Docstring fixes
  Fix issue 5951 - correct __opts__['file_roots'] in ext_pillars
  Expand the `pip` library requirement.
  mention LocalClient.cmd "kwarg" argument in docs
  Added undocumented ssh roster configuration options
  Explain why the pip state needs a pip module importable. Refs #7659.
  except right exception that file module raised
  Prettify subcommand to kill minions
  Removed special case for uppercase attributes from Mock object
  Updated Sphinx makefile for latest Sphinx and i18n additions
  [3665] do not persist gitfs cache dir after config change/restart
  refer to appropriate class (self) in the Caller docstring
  Fixed typo in comment
  Fixed typos and bugs in hgfs. Fixes #7687
  Restore the pillar[master][file_roots] when returning the pillar
  Fix typo
  Have the minion actually generate its ID
  rm unused imports from states/win_system.py
  tomcat module: rm trailing whitespace
  rename code:: to code-block::
  ...
Remove pillar matching for mine.get
Cosmetic adjustment to add some color to the output of sys.doc.
Fix yaml.load refs

These are not really security issues because Salt parses all
incomming arguments via yaml.safe_load before they get here, these
really are not needed. I kept the yaml check in for pillar.ext
simply because we want to be able to support an internal application
firing the routine with a yaml sting.
single quotes
Drop suplimetary groups when running an non-root user
Fix command injection vulnerability in disk.usage
It is better to die(), than to return falsely.
Merge pull request #7774 from techhat/cmdinjection

Fix command injection vulnerability in disk.usage
Merge pull request #7770 from basepi/minepillar7197

Remove pillar matching for mine.get
Merge pull request #7771 from cachedout/develop

Adding some color to sys.doc
Fix command injection flaw in disk.inodeusage
Merge pull request #7776 from techhat/cmdinjection

Fix command injection flaw in disk.inodeusage
Ported gitfs cache fixes from #7749 into hgfs. refs #3665.
Condense df sanitization
Fix minor typo in state logging
Merge pull request #7777 from shadowfax-chc/develop

Ported gitfs cache fixes from #7749 into hgfs. refs #3665.